Is there any chance that someone waved a magnet hear the tube? Remove it and/or move any items like monster speakers away from the set.
Was your kid experimenting with nuclear explosives – an EMP would magnetize the CRT. Nearby lightning strikes may have a similar effect. If demagnetizing does not help, then it is possible that something shifted on the CRT – there are a variety of little magnets that are stuck on at the time of manufacture to adjust purity. There are also service adjustments but it is unlikely (though not impossible) that these would have shifted suddenly. This may be a task for a service shop but you can try your hand at it if you get the service manual – don’t attempt purity adjustments without one. If the monitor was dropped, then it is even possible that the internal shadow mask of the CRT has become distorted and you now have a seventy-five pound boat anchor. 🙁 If the discoloration is slight, some carefully placed ‘refrigerator’ magnets around the periphery of the tube might help. See the section: Magnet fix for purity problems – if duct tape works, use it!
